The tasks involved such things as dragging, holding, or rolling up a heavy hose, stepping over an obstacle carrying a hose, and raking the ground.

The ratio of work to rest mimicked what would happen in an average fire.

Importantly, the firefighters were allowed to pace themselves, take breaks and do whatever they would normally do when fighting a fire - including removing their jackets to keep cool.

The firefighters had their work output, heart rate, core body temperature, skin temperature, and hydration levels measured, and the amount of food and fluid they consumed was also recorded.

"Core temperatures, skin temperatures and how hot they felt were all higher in the hot conditions," Dr Aisbett said.

But, despite this the heart rate between the hot and the control groups remained similar and neither got heat exhaustion.

The hotter temperatures did not make them feel more tired and they kept up with the same level of work output, he said.

Other results of the study pointed to an explanation for this.

The hot group drank twice as much liquid as the other group - not just during the hot weather but the day before the exercise, in anticipation.

"We think that may have helped buffer their body against the extra heat strain," Dr Aisbett said.

Firefighters reduce workload to account for temperature

In a second study, Dr Aisbett found that firefighters were still able to manage heat stress at temperatures reaching 45C, temperatures at which some football matches are cancelled.

In this case firefighters not only consumed more fluid but decreased their work output to manage heat stress.

"Firefighters chose to drop their work rate and their core temperatures stayed at 38.5C," Dr Aisbett said.

He said both experiments suggested firefighters were able to prevent heat exhaustion across a range of temperatures in a way elite athletes who performed continuously did not have the opportunity to do.

He said this was aided by the fact that firefighters had different goals to athletes.

"For an athlete the goal is to win at all costs - to get the best time, best performance, most tackles or whatever the outcome measure is," he said.

"Athletes will push their physiology to achieve their maximal performances and it's OK for them to collapse after the finishing line."

By comparison, he said, the firefighter's goal was to complete the job and keep themselves and others safe.

Dr Aisbett said the research, published recently in the journals PLOS ONE and Frontiers in Physiology, showed the limitations of using sporting research when studying occupations like firefighting and military service personnel.

"We can learn a lot from sport but it's not the perfect proxy of emergency service work," he said.

"Despite similar temperatures, differences in tasks and goals mean the outcomes won't necessarily be the same."

The research also suggests that in extremely hot weather authorities needed to give firefighters more time to carry out their work or bring in reinforcements, to allow for their drop in work output.